Crystals are widely used. They are used from large scintillation crystals to crystal wafers used as substrates in the semiconductor industry, to lenses and mask substrates in the photolitography where purifying, doping and growing crystals continue to require improvements
The present invention includes self-contained crystal melt purifying and doping process and apparatus that are used in vertical, sloped and horizontal crystal growers to melt and purify starter materials and to release crystal material onto a Bridgeman-Stockbarger vertically moving support or onto a sloped or horizontally moving crystal pallet.
Crystal grower and purification stations have material preparation chambers with circular, elliptical, rectangular or polygonal cross-sections. A lateral heater and a base heater are connected for immersion mounting within the chamber. A porous distributor is mounted above the base heater for immersion within the chamber. An opening in a bottom of the chamber releases molten crystal material. A lid mounted on the chamber closes the chamber and forms an enclosed chamber with a closed environment. A crystal material supply, a dopant supply and a reduced pressure exhaust line are connected to the chamber. A purification fluid supply is connected through the chamber to the porous distributor. An external heater surrounds the chamber for heating the chamber and its contents. Insulation surrounds the external heater. An enclosure surrounds the insulation. A gas source and a vacuum line are connected to the enclosure. The external heater includes plural heaters which extend beyond the chamber. A grower mounted below the chamber and within the enclosure for receives the molten crystal material from the chamber. A crucible receives the crystal material and holds the crystal material and a formed crystal. A seed crystal and solid crystal support are mounted within the plural heaters for relatively moving a formed crystal within the plural heaters.
The invention provides a growing and/or purification crystal station having a lateral heater and a base heater. The base heater and the lateral heater are connected for immersion mounting within a chamber. The station includes a porous distributor mounted above the base heater for immersion within the chamber. The chamber surrounds the lateral heater and the base heater. An opening or openings in a lower part of the chamber releases molten crystal material. The chamber surrounds the porous distributor for mounting all of the elements within the chamber. The chamber, heaters and distributor, the crucibles and supports may be circular, elliptical, rectangular or polygonal in cross-section.
A lid is mounted on the chamber for closing the chamber and forming an enclosed chamber with a closed environment. A crystal material supply, a dopant supply and a reduced pressure exhaust line are connected to the chamber. A purification substance supply is connected to the chamber and supplies fluid purification substance to the porous distributor. An external heater surrounds the chamber for heating the chamber and its contents. Insulation surrounds the external heater, and an enclosure surrounds the insulation.
An inert gas source and a vacuum line are connected to the enclosure. Preferably the external heater includes plural heaters, and the plural heaters extend beyond the chamber.
A seed crystal and molten and solid crystal crucible is support mounted within the plural heaters for relatively moving within the plural heaters in a crystal grower. The plate grower is mounted below the chamber and within the enclosure for receiving the molten crystal material from the chamber. The plate grower includes a crucible for receiving the molten crystal material and holding the molten crystal material and a formed crystal. In one embodiment, the crucible comprises dividers for forming plural formed crystals. In other embodiments plural crucibles are stacked or arranged side by side. A formed crystal mover mounted adjacent an end of the crucible for drawing the formed crystal, or moving the crucible.
Plural external heaters extend around the chamber, the crucible and the crystal mover.
Crucible heaters extend near the crucible for heating the molten crystal material and the formed crystal therein. In one form, the crucible heaters comprise plural crucible surround heaters for surrounding the crucible. Preferably at least one of the plural heaters includes a dopant controller.
Other plural crucible heaters include plural proximity surface heaters. Preferably a dopant controller extends into molten crystal material between the proximity surface heaters.
The preferred material preparation chamber comprises a fully contained purification and refill chamber. A purification substance supply is connected to the chamber. A purification fluid source is connected to the porous distributor in the chamber, and a reduced pressure exhaust connected to the chamber. A crystal starter material source is connected to the chamber.
In one embodiment, plural crucibles are positioned within the enclosure and are stacked atop each other below the chamber for receiving molten crystal material.
In one embodiment, plural crucibles are positioned side by side beneath the chamber within the enclosure for concurrently growing plural crystals.
These and further and other objects and features of the invention are apparent in the disclosure, which includes the above and ongoing written specification, with the claims and the drawings.